Process for the preparation of reactive dyestuffs

ABSTRACT

The invention relates to an improved process for the preparation of dyestuffs based on at least one triphendioxazine which is linked to a further chromophore via a triazine at a pH of 5.5 to 2.0 and a temperature of 50 to 100° C.

The invention relates to a process for the preparation of reactive dyestuffs.

Triphendioxazine dyestuffs in which 2 chromophores are linked via a triazine ring are disclosed in US-A-4,005,551. The process for preparing them is needy of improvement.

The object of the present invention is to provide an improved preparation process.

The invention relates to a process for the preparation of dyestuffs of the formula ##STR1## characterized in that a compound of the formula ##STR2## is condensed with a dyestuff of the formula ##STR3## in aqueous medium and in a pH range from 5.5 to 2.0, in particular 5.0 to 2.5, and at a temperature of 50 to 100° C., in particular 70 to 80° C., to give a dyestuff (I), in which

F denotes the radical of a triphendioxazine dyestuff, preferably

F denotes ##STR4## R independently of one another denotes hydrogen, C₁ -C₄ -alkyl or substituted C₁ -C₄ -alkyl

R' denotes hydrogen or a customary substituent of a triphendioxazine dyestuff, in particular halogen, alkyl, alkoxy, carboxyl

T₁, T₂ denote hydrogen, chlorine, bromine, C₁ -C₄ -alkyl, C₁ -C₄ -alkoxy, phenyl or phenoxy, which may be substituted

F₁ denotes the radical of a chromophore.

Examples of R are: CH₃, C₂ H₅, n-C₃ H₇, i-C₃ H₇, n-C₄ H₉, n-C₆ H₁₃, which may be substituted, for example, by OH, OCH₃, OC₂ H₅, COOH, SO₃ H, OSO₃ H, CN, Cl.

Examples of substituents of the optionally substituted C₁ -C₄ -alkyl and C₁ -C₄ -alkoxy radicals T₁ and T₂ are C₁ -C₄ -alkoxy or OSO₃ H.

Examples of substituents of the optionally substituted phenyl and phenoxy radicals T₁ and T₂ are Cl, Br, C₁ -C₄ -alkyl, C₁ -C₄ -alkoxy and SO₃ H.

Examples of suitable substituents R' are the following: halogen, such as Cl, C₁ -C₄ -alkyl, C₁ -C₄ -alkoxy, COOH.

The sulpho group in (IIIa) is in the. opposition relative to the substituent ##STR5##

F₁ preferably denotes a chromophoric radical from the azo, formazan, anthraquinone, phthalocyanine or triphen-, dioxazine dyestuff series, in which the imino group ##STR6## is bound directly to an aromatic-carbocyclic or aromatic-heterocyclic C atom in F₁.

Preference is given to the preparation of dyestuffs (I) in which R is hydrogen and F₁ denotes a radical F. Particular preference is given to the preparation of dyestuffs (I) in which F₁ is identical to F and in which R' represents hydrogen and T₁ and T₂ represents chlorine.

The dyestuffs (II) are obtained by a half-sided condensation of dyestuffs of the formula

    F--H

with cyanuric chloride, such as disclosed, for example, in DE-A-4,005,551, Example 1.

Dyestuffs of the formula (III) are known from the literature in large numbers.

Examples are: ##STR7##

The dyestuffs (II) are preferably used in the form of their lithium salts. Preferably, the reaction is carried out in the presence of a buffer suitable for the pH range from 2.0 to 5.5.

EXAMPLE 1

A neutral solution of the dilithium salt of 2,9-diamino-6,13-dichloro-triphendioxazine-disulphonic acid in 600 ml of water is added at room temperature to 0.05 mol of the di-lithium salt of the dyestuff of the formula ##STR8## (obtainable by condensation of the di-lithium salt of 2,9-diamino-6,13-dichloro-triphendioxazine-disulphonic acid with cyanuric chloride in the presence of lithium hydroxide) present in 700 ml of water. The pH is brought to 5.0 with 2 ml of phosphoric acid, and the reaction mixture is then heated to 75° C. During condensation, the pH drops to about 2.5 to 3. After about 8 to 10 hours, the reaction is complete. The pH is then brought to pH 7 with lithium hydroxide solution. The dyestuff is precipitated by adding about 4% by volume of sodium chloride and can be isolated by filtering it off with suction.

In the form of the free acid, it has the formula ##STR9##

EXAMPLE 2

10 g of cyanuric chloride are added to 0.1 mol of 2,9- diamino-6,13-dichloro-triphendioxazine-disulphonic acid, which is dissolved in 1.3 l of ice water as the neutral di-lithium salt, and condensed in a pH range from 5 to 5.5, which is maintained by dropwise addition of dilute lithium hydroxide solution. After about 3 to 4 hours, 50% of the triphendioxazine dyestuff have been acylated on half a side. The mixture is heated to 72 to 74° C, during which the pH is allowed to drop to 3.5 and then maintained at 3.5 to 4.5 by adding dilute lithium hydroxide solution. After about 8 to 10 hours, condensation is complete. The mixture is brought to pH 7 and the dyestuff is salted out with 4 % by volume of sodium chloride. The dyestuff is identical to the product obtained according to Example 1. 

I claim:
 1. Process for the preparation of dyestuffs of the formula ##STR10## in which F corresponds to the formula ##STR11## wherein R' denotes hydrogen or a customary substituent of a triphendioxazine dyestuff,T₁ and T₂ denote hydrogen, chlorine, bromine, C₁ -C₄ -alkyl, C₁ -C₄ -alkoxy, phenyl, or phenoxy, which may be substituted, R, independently of one another, denotes hydrogen, C₁ -C₄ -alkyl, or substituted C₁ -C₄ -alkyl, and F₁ denotes the radical of a chromophore,whereby a compound of the formula ##STR12## in the form of its lithium salt is condensed with a dyestuff of the formula: ##STR13## in aqueous medium and in a pH range from 5.5 to 2.0 and at a temperature of 50 to 100° C.
 2. Process according to claim 1, characterized in that the reaction is carried out in the presence of a buffer.
 3. Process according to claim 1, characterized in thatR is CH₃, C₂ H₅, n-C₃ H₇, i-C₃ -H₇, n-C₄ H₉, n-C₆ H₁₃, which may be substituted by OH, OCH₃ OC₂ H₅, COOH, SO₃ H, OSO₃ H, CN, Cl, R' is Cl, C₁ -C₄ -alkyl, C₁ -C₄ -alkoxy, COOH.
 4. Process according to claim 1, characterized in thatR is H, F₁ is F, R' is H, T₁, T₂ are Cl
 5. Process according to claim 1, characterized in that the dyestuff in the form of the free acid has the following formula ##STR14## 